Effect of winter feeding and starvation on the growth performance of young-of-year (YOY) great sturgeon, Huso huso

The objective of this study was to evaluate the feeding rate of the great sturgeon (Huso huso) young of the year (YOY) and to investigate the effects of different feeding rates in maintaining the weight of fish during short periods of winter starvation. Six feeding rates of 0.2, 0.4, 0.6, 0.8, 1.0% body weight (BW) day-1 and feeding to satiation were considered for the first experiment. Each feeding rate was randomly assigned to three replicate tanks, with continuous feeding throughout a 5-week winter period of water temperatures below 10 degrees C. Fifteen fish were held in each of 18 tanks with an average initial body weight of 219.6 +/- 6.9 g. After 5 weeks of feeding, the best performance was observed in fish fed 1% BW day-1, but negative growth was observed in fish fed 0.2% BW day-1. In the second experiment, fish were deprived of feed for 3 weeks at winter temperatures. Weights and condition factors of all fish decreased during starvation, while the differences in mean weight before and after the starvation period were not significant in fish fed a level of 0.2% BW day-1 and those fish fed to satiation. No mortality was recorded in either experiment. Results of this study indicate that a feeding rate of 1% BW day-1 would be sufficient for commercial fish farming of YOY of this species to maintain them over winter. Also, to maintain fish weights and prevent weight loss in overwintering ponds, a feeding rate of around 0.3% BW day-1 seems appropriate for hatcheries.